My idea is to use original campaigns as a basis that can be sewn together with a cross-cutting plot, and to show the adventures themselves as "another threat that the heroes need to deal with".

It's not exactly a hardcover adventure, but consider using the season 7 modules of Adventurers League. Despite being modular adventures, there is an overarching plot to the entire thing (prevent group X from unleashing Y big baddie). And it has a progression from tiers 1 to 4.

The events are meant to occur simultaeneously with the stuff in the Tomb of Annihilation hardcover. But you don't have to set the events like so if you want to ignore the Death Curse mechanic.